High-voltage stator coils are used in high-voltage electrical generators. A stator coil can be formed including an electrical conductor bar that, in turn comprises one or more electrical conductors. The electrical conductors individually are formed of a highly conductive material, such as copper. The electrical conductors are bundled together to form the conductor bar.
In one prior art configuration of a stator coil, an inner corona protection system is provided over an electrical conductor bar comprising a first layer of mica paper tape applied directly over the conductor bar, which first layer of mica paper tape may be referred to as a “top cap.” The top cap is applied over the conductor bar such that a first end portion of the conductor bar is exposed and is not covered by the top cap. A second mica paper tape layer is edge lapped about the conductor bar and the top cap. The second layer is applied over the conductor bar such that the first end portion of the conductor bar is exposed and is not covered by the second layer.
A conductive structure, such as a thin copper strip, is applied over the conductor bar, the top cap, and the second layer. A first end of the conductive structure contacts the exposed first end portion of the conductor bar. An intermediate portion of the conductive structure contacts the second layer of mica paper tape. A second end of the conductive structure is not in contact with the conductor bar or the second layer of mica paper tape. A conductive tape layer is edge lapped about the conductive structure, the top cap, and the second layer of mica paper tape, but not over the exposed first end portion of the conductor bar. The conductive structure transfers the electrical potential from the conductor bar to the conductive tape layer, such that the conductor bar, the conductive structure, and the conductive tape layer are all at the same electrical potential.
A total thickness of the applied top cap, the second layer of mica paper tape, the conductive structure, and the conductive tape according to this prior art configuration may be from about 0.019 inches to about 0.023 inches.